The invention refers to a manual device for the transfer of film from a tape applicator and more particularly the present invention relates to a return stop for preventing undesired back rotation of a reel.
In a manual device for transferring a film from a backing strip to a substrate (alternately referenced herein as a tape applicator for the sake of convenience), the backing strip carrying the film is supplied on a supply reel, drawn over an applicator tip, at which the backing strip is pressed against the substrate to apply the film, and taken up on a take-up reel. When in an operating mode, the film is withdrawn from the supply reel by a manually generated movement, by means of which the manual device is moved along the substrate, the film being released from the backing strip and the backing strip simultaneously being wound off of the supply reel and onto the take-up reel. To guarantee this mode of operation, the speed at which the material is wound onto the take-up reel must be at least as great as the speed at which it is unwound from the supply reel as otherwise loops would form during recoiling, which could lead to the manual device being unable to function. A drive connection is provided between the supply reel and the take-up reel for the purpose of this specific function which drives the take-up reel in a transmission ratio such that the take-up speed is greater than the unwinding speed of the supply reel. It must be remembered here that the effective outer diameters of the supply reel and the take-up reel are constantly changing as the backing strip is unwound from the supply reel and wound onto the take-up reel. This problem is solved firstly by the drive connection driving the take-up reel so quickly that firstly the winding speed effective there is always the same or greater than the unwinding speed and namely even when the outer diameter of the take-up reel is at its maximum and the outer diameter of the supply reel is at its minimum, and secondly by the drive connection functioning with slip such that although the take-up reel is driven with a constantly effective torque so that the section of backing strip being wound on is under tension, at the same time the slip is effective within the drive connection so that the section of backing strip being wound onto the take-up reel does not tear.
A further problem with the mode of operation of an existing manual device consists of the fact that both the supply reel and the take-up reel each tend to run backwards somewhat after a rotary movement caused by removing the backing strip, which can be caused by stresses in the backing strip. The reels reversing in this way can also cause small loops which can impair the function of the manual device.
A manual device of the type described above, has been described, for example, in patents EP 0 267 396 B2 (corresponding to U.S. Pat. No. 4,851,076 to Manusch et al.), EP 0 680 914 D1 (corresponding to U.S. Pat. No. 5,577,007 to Czech et al.), EP 0 656 308 D1 (corresponding to U.S. Pat. No. 5,556,469 to Koyama et al.), and DE 39 00 156 C2 (corresponding to U.S. Pat. No. 5,049,229 to Czech). In one existing manual device, the supply reel and the take-up reel can be mounted so that they can rotate around axes of rotation which are arranged at a distance from each other, or they can also be mounted so that they can rotate around a common axis of rotation, as described in DE 39 00 156 C2 (corresponding to U.S. Pat. No. 5,049,229).
In the manual device described in EP 0 267 396 B2 (corresponding to U.S. Pat. No. 4,851,076), the drive connection between the supply reel and the take-up reel is formed by a gear wheel drive with an intermediate gear wheel, the return stop meshing with the intermediate gear wheel and being formed by at least one sprung tongue, which is fixed to the housing and meshing with the teeth of the intermediate gear wheel with its sprung free end, the said end extending as a secant. This known design not only contains a large number of elements, but also requires a relatively large space for installation because both the intermediate gear wheel and the sprung tongue must be housed in an unobstructed region inside the housing.
In the manual device described in EP 0 680 914 (corresponding to U.S. Pat. No. 5,770,007), in which the drive connection between the supply reel and the take-up reel takes the form of a friction wheel drive, a return stop for the take-up device is formed by a toothed surface on the radial face surface of a bearing bush of the recoiling reel (see FIG. 3), the toothed surface meshing with opposing gearing on an opposite surface fixed to the housing. In this known design, the take-up reel must execute small axial movements when rotating through the return stop while operating, the said movements being disadvantageous for both the friction wheel drive and for taking up the backing strip, an additional spring element also being required which strikes the take-up reel with its toothed surface against the opposing gearing.
A design similar to the design described above is provided in a manual device according to EP 0 656 308 (corresponding to U.S. Pat. No. 5,556,469). In this known design, the drive connection between the supply reel and the take-up reel is also formed by a friction wheel drive, the return stop meshing with the take-up reel and being formed by a locking pawl arranged in a cut-out of a friction wheel arranged on the take-up reel, which has a pawl on its free end and is pretensioned elastically with this against a toothed surface, which is formed on an additional toothed ring, and is fixed to the housing on an internal surface of the housing. This known design also needs an additional component, namely the toothed ring, whereby it is also to be expected despite the elastic flexibility of the locking pawl, that if the return stop is turned too far, the take-up reel will make axial movements or will at least be pushed in the direction of axial movements. Therefore, increased wear is to be expected because only a relatively small annular surface on the body of the reel is available as the mounting for the take-up reel.
A manual device is described in DE 39 00 156 C2 (corresponding U.S. Pat. No. 5,049,229), in which the supply reel and the take-up reel are arranged side by side in a coaxial arrangement, the drive connection being arranged between the reel walls, which are adjacent to each other, and being formed by a coupling tooth, which is arranged on a sprung arm which projects radially from the one reel wall and therefore can be moved radially and is struck radially outwards against a gear ring on the other reel wall using elastic pretensioning of the sprung arm. The teeth of the gear ring and the coupling tooth have angled tooth flanks so that the coupling tooth is forced out of the gaps between the teeth when a certain tensile stress is exceeded in the take-up section of the backing strip and the above-mentioned slip takes place in the drive connection. This known design therefore involves a slip clutch in the drive connection between the reels, both components being rotating components. This friction clutch cannot fulfill the function of a return stop. Therefore a return stop is provided which meshes with the supply reel, which is formed by an engaging finger, which meshes with a gear ring on the supply reel in the form of a locking pawl. This design of a return stop is also expensive and has large dimensions and an interior space of a considerable size having to be present for the engaging finger to enable it to be arranged so that it can function. This also leads to a large format for the manual device as a whole.
The present invention provides a compact device for transferring a film from a backing strip to a substrate, or xe2x80x9ctape applicator,xe2x80x9d that is economical to manufacture. In accordance with the principles of the present invention, first and second bearing components are provided in coaxial engagement in the device. The first and second bearing components rotate relative to each other and a return stop is provided therebetween to prevent undesired backward rotation. The present invention is compact, as it permits a return stop to be arranged within the axial projection region of the bearing components, thus causing it to have scarcely any negative effect on the interior of the housing.
Moreover, in accordance with the principles of the present invention the return stop may be formed with a locking pawl arranged on one bearing component so that it yields elastically against a spring force, and a gear ring arranged on the other bearing component. Thus, the present invention also permits the locking pawl to operate reliably between the bearing components, the associated reel (associated with the bearing component on which the locking pawl is provided) not participating in the movements of the locking pawl, thus enabling the locking pawl to remain in position axially while in its operating position. Moreover, the present invention can be manufactured simply, little material being required because the locking pawl according to the invention can be produced in a compact format while guaranteeing reliable operation.
It is advantageous for the locking pawl to be arranged so that it is movable radially or yields radially. In this case, unused spaces which are radially adjacent with respect to the locking pawl can be utilized, into which the locking pawl can move, e.g., the unused space inside the housing or an unused space inside the inner bearing component, especially if the latter is formed by a hollow, cylindrical journal to save material and weight.
If the locking pawl is arranged on the free end of a pawl arm, it does not require an additional spring element to knock the locking pawl into its operating position, because the intrinsic elasticity of the pawl arm can be used as the spring force. Thus it is possible within the scope of the invention for the pawl arm to extend parallel to the axis of rotation of the relevant reel or to run curved in an arch shape around the axis of rotation. The latter configuration particularly permits a narrow format because the length of the pawl arm is normally to be greater than its width.
The device according to the principle of the present invention also permits a compact format in the axial direction in this case because the locking pawl can be arranged in the region in which the bearing components overlap, therefore within the bearing region. Here the locking pawl can be arranged in the region of a cut-out in the bearing component concerned. A space is created in this way in which the locking pawl can move.
Moreover, it is advantageous for the gear ring of the locking pawl to be arranged countersunk in the bearing component concerned, while the locking pawl is arranged in such a way that, in its operating position, it projects beyond the bearing joint, which is present between the bearing components and is particularly of a hollow cylindrical design and engages in the gaps between the teeth of the gear ring. In a design of this type, putting the bearing components together axially is not impaired during assembly of the manual device because the locking pawl can move out of the way radially when the components are being pushed together axially and therefore the locking pawl is not in the way of the relevant edges of the other bearing component. Furthermore, it is advantageous for two locking pawls to be arranged opposite each other, as a result of which the locking effect can be increased if the locking pawls are of a slightly yielding design. It is an advantage here to offset one locking pawl in such a way in the circumferential direction that when the one locking pawl is in a gap between the teeth, the other locking pawl is on a tooth of the gear ring. As a result, even if the tooth angles are relatively flat, which is desirable for reasons of ease of movement, small locking sections achieve a reverse movement of the reel concerned, which counters the formation of loops effectively.
The devices formed in accordance with the principles of the present invention can be formed on the existing components as single components so that no additional components are necessary. A manufacturing process involving injection-molding is particularly suitable, especially if the relevant components of the manual device are made of plastic. Thus the locking pawl acts between the bearing components in all the designs according to the invention, namely in a region of the cavity of the housing in which the locking pawl does not disrupt the cavity and is therefore also unable to disrupt the cycle for the backing strip.